Logo
FULL SITE MENU

My Tohasu 30 hp wouldn't start

H

hajdu

New member
I have had this engine for two years without any major issues, then few weeks ago after a half hour it has stopped and I'm unable to fire it up.
I have checked the fuel injection system, all sensors and switches (MAT, Water temp sensor, oil pressure switch, stop switch, MAP, TPS, ISC, etc)
The only thing I can pinpoint is the FFP high pressure pump wouldn't get any voltage. Would anybody know what is needed in order to sort this?
I can only that it's not the ECU as it costs and arm and a leg to replace it. Since I'm living in Hungary it is nearly impossible to find a garage who could fix this.
Any help would be greatly appreciated.
 
You did not say, but I assume your model is MFS30C.
The FFP gets signal from the ECU, so a bad ground, broken wire or defective ECU could cause this. Is there 12v coming from the ECU? If so, check wiring. If not, look at the ECU.
 
pvanv said:
You did not say, but I assume your model is MFS30C.
The FFP gets signal from the ECU, so a bad ground, broken wire or defective ECU could cause this. Is there 12v coming from the ECU? If so, check wiring. If not, look at the ECU.
Click to expand...

Hi Paul,
Thanks for your reply. You've almost guessed it, I have an MSF30B model.
The 12v is indeed coming out of the ECU, it seems the FFP wouldn't get ground from there.
Simultaneously the A1 ECU (which is on the same circuit) is getting the ground (for the warning lamp and the buzzer).
I have checked the wiring but couldn't find anything suspicious, it is driving me mad.
Is it possible to put the A1 on ground (temporarly as a test) without any dire consequences?
Thanks for your help, really appreciate it.
 
pvanv said:
If you have 12v at the ECU but not at the pump, odds are you have a bad wire.
Click to expand...
Hi Paul,
Thanks for your reply again.
I have tested every single wire manually (one-by-one), so that can't be the problem.


Unfortunatelly it is possible that my approach was wrong. When starting the engine the ECU does indeed give the 12v (+) on A1.
This then goes to the FPP (led and buzzer) and then to the A22. Is this where it supposed to get ground?
When starting the engine is it possible top ut this (A22) on ground, without messing up the ECU?

Is it possible that the ECU is messed up already? Am I missing any criteria for the pump to start?
Also, is there a place (website, forum or anything else) where I could find a schematic of the ECU?
Thanks in advance
 
Last edited:
A1 is 12v to the FPP (and others).
A22 is neutral to the FFP. It should already show as ground.
No one outside of Japan has a schematic of the ECU.
So, if you have 12v at the pump, then the pump has an issue.
 
Hi Paul,
Thanks for your reply.According to the measurement, the ECU A22 point is not a body (GND). Resistance to the body (GND) (7.7 KOHM or 8 KOHM) for polarity polarity.
Does this point in the ECU inside something (condition) bodies?
FFP goes from a separate power supply.,
 
Last edited:
I cannot measure 12v at the pump, because the pump doesn't seem to have ground (hence the reason it's not working)
To me it seems that the only logical reason for this error is that something is stopping the ECU to allow grounding the A22.
As I stated above (sorry for my bad english, I was using Google Translate but the forum wouldn't let me edit my previous message), the FFP does work using a separate power supply






 
Last edited:
pvanv said:
You could try it to test. If the ECU is shot, it won't hurt.
Click to expand...

The engine is starting this way, the engine is running :)
The only issue is the initial higher engine speed, it wouldn’t go down until the engine is warmed up.
When I put it in gear I cannot alter the engine speed, it is constant.

Can you suggest what could I do please?
Thanks Paul
 
Last edited:
I'm sorry but I was sick for a long time.You will re-start the bugs. At the ECU, the A22 point does not give a body. This should be fulfilled by this condition to do so. Otherwise, A22 would be a smooth body. So only a couple of Kohm are measured .. Help you where I can turn around. Thanks for the reply
 
Back
Top